This invention relates to a network monitoring system for monitoring a communication path established on a communication network.
The development of network techniques such as IP (Internet Protocol), MPLS (Multi-Protocol Label Switching), etc., and content delivery techniques such as World Wide Web or Contents Delivery Network, etc. have enabled the use of a communication network as a delivery base for large capacity files such as a dynamic picture image, etc., and for streaming data. High reliability of the delivery base is indispensable to safe utilization of such a communication network as a social base, and the ability to monitor obstacles, construction, flow rate, performance and security of the communication path is also indispensable.
To monitor the communication path, it is necessary to obtain the states of a device constituting the communication network and the communication path virtually constructed by this device. Specifically, monitoring manager equipment (hereinafter “monitoring manager”) and monitoring an agent device (hereinafter “monitoring agent”) are used. The monitoring manager obtains state information of the communication path and a data processor using a management protocol such as SNMP (Simple Network Management Protocol, IETF RFC1157), CMIP (Common Management Information Protocol, X.711, ISO/IEC 9596-2), etc. from the monitoring agent connected to the communication path and data processor, and displays the state information.
To obtain the state information of the communication path, it is necessary to give the monitoring agent device, as a monitoring object, the following information: instructions about the communication path, a monitoring item, a method for notifying the monitoring manager, and a notifying frequency, as well as other information.
For example, IETF RFC2720 “Traffic Flow Measurement: Meter MIB measures traffic flowing through the IP network. However, it is necessary to assign the traffic flow as a measuring object in advance with respect to the meter as the monitoring device. Transmission/arrival IP addresses, a transport protocol classification, and transmission/arrival port numbers, are assigned.
In this case, the data processor is a device for transferring, accumulating and processing a data frame, a packet and contents. For example, the data processor includes a transmission device such as SDH (Synchronous Digital Hierarchy), etc., a packet transfer device such as an IP router, an MPLS switch, an asynchronous transmission mode (ATM) switch, etc., a computer such as a WWW server, a data cache, a load dispersion device, etc. The communication path is the flow of the IP network, a Label Switched Path of the MPLS, a session established via a proxy server between the WWW server and a client, etc.
The following procedures are carried out to monitor the communication network once the communication path is established by transmitting and receiving communication-path-establishing control information between the data processors using a conventional system. First, it is necessary for the monitoring manager to know through which data processor a certain communication path is formed within the communication network. Therefore, constructional information for the communication path is obtained from the data processor. Next, the monitoring manager determines a monitoring agent device for obtaining the attribute value of a monitoring object on the basis of the constructional information. The monitoring manager then gives the monitoring agent, as the monitoring object, the following information: instructions regarding the communication path, a monitoring item, a method for notifying the monitoring manager, a notifying frequency, etc. The monitoring manager collects the attribute value obtained by the monitoring agent device. Processing the collected data as a display on the screen of the monitoring manager equipment, etc. is performed with respect to the collected attribute value.
In this case, the attribute of the communication path is obstacle information such as the existence or nonexistence of an obstacle, etc.; constructional information such as a list of used resources, etc.; account information such as a passing or processed packet; the flow rate of contents, etc.; performance information such as a time required for the passage; a loss rate, etc.; security information such as the past record of an unfair establishing request of the communication path, etc. When the communication network is monitored by using the above method, the following problems are caused.
First, a large amount of management traffic is generated when the monitoring manager obtains the construction of the communication path from the data processor and sets the monitoring of the monitoring agent device. The processing load is concentrated on the monitoring manager. Second, a monitoring error is often caused since it is difficult to conform the period of the communication path establishment and the period of a monitoring start. Data can be instantly transferred after the communication path is established. However, the monitoring can be started only after the monitoring manager obtains the construction of the communication path, and the monitoring item, etc. are sent to the monitoring agent device. These processing times become a measuring error. In particular, this error becomes significant when a large amount of data is transferred for a short time, as in the remote backup of a large capacity file, etc., and the communication path is frequently established/opened as in WWW browsing. Third, is a case where the data processor is used in the communication path, i.e., the communication path is changed by autonomic switching processing of the data processor after the communication path is established. However, it is difficult to cope with this change in the conventional system. Accordingly, an improved monitoring method is needed.